Question

I have two classes :

SQL Connection Class

   class MysqlDB {

   protected $_mysql;
   protected $_where = array();
   protected $_query;
   protected $_paramTypeList;

public function __construct($host, $username, $password, $db) {
      $this->_mysql = new mysqli($host, $username, $password, $db) or die('There was a problem connecting to the database');
   }

   public function query($query) 
   {
    //...................... }

   public function __destruct() {
        $this->_mysql->close();
   }
}

User Class

class cUser {

    private $_name;
    private $_email;
    private $_password;

    public function __construct() {
        $this->_name = '';
        $this->_email = '';
        $this->_password = '';
    }

    public function getUser($username) {
        global $db;
        return $db->query("SELECT * FROM user where username='$username'");
    }


}


**index.php**
<?php
require_once('cMysqlDB.php');
require_once('cUser.php');

$db = new MysqlDB('host','username','password','db');
$user = new cUser();
$userData = $user->getUser('username');
print_r($userData);
?>

Totally works! Thanks to Sabeen Malik

Answer 1

Though I am not entirely sure why you are inheriting the Users from the MySQL class. But anyway, if you really need to do it that way.

Instead of

$this->_conn = new MysqlDB($host, $username, $password, $db);

do:

parent::__construct($host, $username, $password, $db);

You don’t need the $this->_conn just use $this->_mysql

I believe the MysqlDB class would be in the singleton pattern. The User class would just use the methods of the MySQLDB class by talking to its object like :

$results = MySQLDB::instance()->query(whatever);

or something on those lines. Some people even use a global $db object and use that in their classes ( i am not condoning that though ) but there are several ways to go about this. I am not sure if you have chosen the right one.

Edit:
Using the global $db, you can get the user data like this:

class cUser {

    private $_name;
    private $_email;
    private $_password;

    public function getUser($username) {
        global $db;

        return $db->query(whatever);
    }
}